The present invention broadly relates to a method of grinding gear teeth and, more specifically, pertains to a new and improved method of controlling the grinding stroke in a gear tooth flank grinding machine.
Generally speaking, the method of the present invention controls the grinding stroke or path length in relation to the generating path or travel of a gear tooth flank grinding machine operating on the indexing generating principle and having at least one dished or conical grinding wheel reciprocatably movable along involute gear tooth flanks.
More specifically, the method of the present invention controls a grinding stroke H of a gear tooth flank grinding machine operating on the indexing generating principle and having at least one dished or concave grinding wheel with an active radius R.sub.S reciprocatably moveable in grinding strokes along generatrices of involute gear tooth flanks to perform a machining of each gear tooth flank and wherein the grinding stroke H is greater than lengths of the generatrices by the amount of a supplemental dimension.
When machining involute gear tooth flanks, especially on helical gears, a grinding operation is carried out along the generatrices which extend over variable lengths in the width of the gear tooth; it is therefore advantageous to control the grinding stroke in relation to the functionally required lengths in order to avoid unnecessarily great over-runs of the grinding wheels. Such over-runs represent idle time for the grinding machine in which no work is performed on the gear blank.
It is known from U.S. Pat. No. 3,753,319, granted Aug. 21, 1973, to define a parallelogramatic grinding stroke zone in relation to the helix angle of the gear teeth to be cut by means of stop abutment rails which, at least to a rough approximation, corresponds to the varying required grinding stroke lengths. The stop abutment rails are empirically adjusted at the beginning of the grinding operation on a gear or a series of gears; once the rails have been adjusted it is not possible to change them during the grinding operation and the geometrical possibilities presented by the form of the gear tooth flanks in individual cases cannot be fully exploited.
Furthermore, the diameter of the grinding wheels have hitherto been regarded as constant during the entire machining operation for the purposes of controlling the length of the grinding stroke, even through grinding wheels which are employed for grinding large gears, have, when new, a diameter of from 500 to 700 millimeters and which wears down to a diameter of from 250 to 300 millimeters. In failing to adapt the control of the grinding stroke length to the decreasing diameter of the grinding wheels, considerable portions of the operating time of the grinding machine are wasted.